Cli
* CLI: submission delete-assay command is added. After deleting assay file, command downloads the latest metadata files from MetaboLights study. ([`f6b1ff5`](https://github.com/EBI-Metabolights/metabolights-utils/commit/f6b1ff580bc29484f392e73128d4985fe8ad3037))
Documentation
* docs: README document and command message updates. ([`1428f25`](https://github.com/EBI-Metabolights/metabolights-utils/commit/1428f25c652ed0bf9fd70e2b7cb284c2d51f3e31))